Switch assembly for printed circuit boards



April 13, 1965 G. M. FARRELL 3,178,523

SWITCH ASSEMBLY FOR PRINTED CIRCUIT BOARDS Filed June 1, 1961 /5 l9 [:7 J l8 [H8 2 0 I za a 0 Fig.5 (36 FIG. 4

TI-THI-TI-IEF JNVENTOR. Guy M. Farrell BY 0m, 2 0my0Z meld-w he??? United States Patent 3,178,523 SWITCH ASSEMBLY FOR PRINTED CIRCUIT BOARDS Guy M. Farrell, Elmhurst, Ill., assignor to F & F Enterprises, Inc., Chicago, Ill., a corporation of Illinois Filed June 1, 1961, Ser. No. 114,263 4 Claims. (Cl. 20016) This invention relates in general to an electrical switch construction and more particularly to an improved switch arrangement of extremely small size.

Among the problems in switch construction is that of guarding against contact erosion or the results of arcing while securing alignment of the contacts and their closure under the required degree of spring pressure. It is further desirable to have the biasing spring for the contacts divorced from current flow and to have all contacts simultaneously operated from a common source of power. In addition there are problems relating to the manufacture and assembly of such contacts, especially when they are limited in dimension such as those commonly known as micro switches.

It is accordingly an object of this invention to provide a contact arrangement in which the possibility of contact erosion affecting the contacts is reduced and in which other contact problems are avoided.

It is a further object of this invention to provide a contact arrangement in which the contacts are biased by a spring which is divorced from current flow.

It is a further object of the present invention to provide a single pole double throw switch of unusual economies of construction and design.

It is a further object of the present invention to provide a plurality of single pole double throw contact arrangements in a single housing which may be mounted facily on a printed circuit board.

Other objects together with the features of this invention will become apparent upon examination of the following specification, claims and drawing wherein FIG. 1 is a perspective view of the contact arrangement assembled on a printed circuit board;

FIG. 2 is a top plan view of the contact arrangement housing;

FIG. 3 is a side elevational view of the contact arrangement shown in FIG. 1;

FIG. 4 is a bottom elevational view of the contact arrangement shown in FIG. 1; and

FIG. 5 is a sectional view illustrating several single pole double throw arrangements used in the switch.

In FIG. 1 the contact structure is illustrated. It comprises a U-shaped housing in which the bar of the U forms the top wall 12 while the legs 14 form the side walls. An end Wall 16 is formed from the bar 12 and depends therefrom at right angles to the legs 14. The end wall 16 forms a stop for the actuator 20 which comprises an insulating member 19 preferably of plastic and carrying a metal strip 22 which conforms to a portion of the perimeter of the member 19. As seen in FIG. 5 the actuator 19 has a cutout portion in which a coil spring 36 is seated against the bend 35 of the strip 22 on one side and on the other side against the projection 37 on the end walls 16. This spring 36 biases the actuator in a direction away from the end wall 16. However, the projections 21 on the actuator 20 engage the side legs 14, which act as a stop.

Supporting the bottom of the actuator in the housing is an insulating member which has a series of apertures through which the various terminals 30 extend. The insulating member 15 is clamped to the U-shaped housing by the flanges or cleats 27 and 28 formed on the side legs 14 and end wall 16 respectively. In addition the side 3,178,523 Patented Apr. 13, 1965 ice legs 14 and end wall 16 are provided with the projections 18 which enable the contact structure 10 to be mounted on a printed circuit board 24 with the terminals 30 engaging the respective terminals 32 on the board 24. It will be noted in FIG. 4 that six terminals are provided in each of two rows. The center terminal of three in each row serves as the common pole for one terminal on each side.

The terminals 30 each comprise a shaft which is tightly seated in the respective apertures of insulating member 15 and each has a flattened portion 47 against which one of the spheres or balls 45 is adapted to engage. A pair of the spheres 45 are assigned to each of a plurality of recesses 41 in the member 19 and each recess 41 is assigned to three terminals 30. A pair of such recesses 41 are shown in FIG. 5, it being understood that these are on one side of the member 19 and that another two such recesses are supplied on the other side of member 19. The bottom of the actuator 19 between its side walls is cut away as at 49 to enable the actuator to ride past the tops 47 of terminals 30.

The spheres 45 are biased against the portions 47 by the respective springs 42 preferably formed of an electrically conductive material and whose force is transmitted equally to the spheres by the plate 44 also preferably formed of an electrically conductive material electrically to interconnect the pairs of spheres as well as to function as the leveling member. The sides of the recesses 41 are spaced to center each ball 45 over a respective terminal 30 and to position the pair of balls over adjacent terminals and against each other whereby a circuit may be completed from one terminal 30 through one of the spheres 45 to the other sphere 45 or through the plates 44 or spring contact common with the pairs of spheres and from and to the other engaged terminal 30.

When the actuator 20 is moved against the bias of spring 36, the sides of the recesses 41 carry the respective pair of spheres 45 in the same direction. This causes the spheres 45 to disengage the respective pair of terminals 30. The sphere 45 which engaged the end terminal of three now engages the center terminal, while the sphere 45 which engaged the center terminal now engages the other end terminal. It will be noted that spheres 45 bridge the terminals 30 during the transit.

On release of the actuator 20 it returns to its original position under the influence of spring 37 to reestablish the original circuit condition for spheres 45 and terminals 30. The spheres, of course, roll as they move thereby being wiped free of dirt and in addition are enabled to present diiferent points of contact to each other and to terminals 30 for reducing the effects of arcing. Further, since contact is at tangent points adequate contact pressure is easily secured.

While the invention has been described with reference to a pair of aligned switch assemblies on each side of the block to provide for four micro switch systems, it will be understood that the inventive concepts are applicable to a single switch unit embodying a pair of balls and three contact points arranged on one side or to more than two units in linear alignment or to any number of units in linear alignment as well as any number of rows of such linearally aligned units to provide for a multiple micro switch arrangement, all of which are simultaneously operated upon displacement of the pairs of balls in each unit from one position to the other. Thus, the invention may be embodied in a structure having one, five, six, eight, twelve, etc., pairs of balls and three aligned contacts in lengthwise alignment in spaced a part relation or any number of rows of one or more such lengthwise aligned pairs of balls and contacts to provide a multiple switching arrangement.

Thus having described one embodiment of my invention but believing it to be broader than the disclosed arrangement, there is appended hereto a series of claims whose scope is believed more adequately to cover the disclosed invention.

I claim:

1. A switch assembly for use with a printed circuit board comprising a U-shaped housing having an end wall in a plane perpendicular to the side legs of said U, an actuator movably located between the legs of said U, biasing means located between said end wall and one end of said actuator for urging said actuator in one direction, said housing having an open end opposite said end wall, said actuator having an actuating portion normally extending outwardly of said housing through said open end in response to the action of-said biasing means, projecting means formed in said actuator and recess means formed in at least one of the side legs of said U, said projecting means being adapted to engage said recess means whereby the wall of said recess means acts as a stop for said actuator when moved in said one direction by said biasing means, an insulating member positioned adjacent one wall of said actuator, means for holding said insulating memher in position, a plurality of terminals extending through said insulating member, at least one recess defined by said actuator, said actuator recess being dimensioned so that two of said terminals are encompassed by the actuator recess, a pair of contacts in said actuator recess biased to engage a respective one of said two terminals and adapted to be moved from the respective terminals upon movement of said actuator in opposition to said spring toward said end wall whereby said contacts engage another combination of two terminals upon completion of said movement.

2. A switch assembly for use with a printed circuit board comprising a U-shaped housing having an end wall in a plane perpendicular to the side legs of said U, an actuator movably located between the legs of said U, biasing means located between said end wall and one end of said actuator for urging said actuator in one direction, said housing having an open end opposite said end wall, said actuator having an actuating portion normally extending outwardly of said housing through said open end in response to the action of said biasing means, projecting means formed in said actuator and recess means formed in at least one of the side legs of said U, said projecting means being adapted to engage said recess means whereby the wall of said recess means acts as a stop for said actuator when moved in said one direction by said biasing means, an insulating member positioned adjacent one wall of said actuator, means for holding said insulating memher in position, a plurality of terminals extending through said insulating member, a recess defined by said actuator, said actuator recess being dimensioned so that two of said terminals are encompassed by this recess, a pair of spheres in said actuator recess biased to engage a respective one of said two terminals and adapted to be rolled from the respective terminals upon movement of said actuator in opposition to said spring toward said end wall whereby one of said spheres engages another of the two terminals while the other of said spheres engages a third terminal.

3. The switch claimed in claim 2 in which said spheres are biased by a spring, and a member tangential to said spheres and located between said spheres and spring.

4. The switch claimed in claim 2 in which said actuator has a plurality of recesses each having a pair of spheres engaged therein for engaging a respective pair of terminals with one of said spheres in each recess adapted to engage a third terminal and the other sphere in each recess adapted to engage the terminal vacated by said one sphere.

References Cited by the Examiner UNITED STATES PATENTS 1,740,535 12/29 Bramming 200166 X 2,246,373 6/41 Lodge ZOO-16 2,303,693 12/42 Hill 200-16 2,528,035 10/50 Clayton ZOO-16 2,528,115 10/50 Clayton 200-46 2,627,006 1/53 Lawson et a1 200166 X 2,710,317 6/55 Pearl.

2,902,550 9/59 Allison 200-l 6 3,015,001 12/61 Woofter 200-16 X BERNARD A. GILHEANY, Primary Examiner. MAX L. LEVY, Examiner. 

2. A SWITCH ASSEMBLY FOR USE WITH A PRINTED CIRCUIT BOARD COMPRISING A U-SHAPED HOUSING HAVING AN END WALL IN A PLANE PERPENDICULAR TO THE SIDE LEGS OF SAID U, AN ACTUATOR MOVABLY LOCATED BETWEEN THE LEGS OF SAID U, BIASING MEANS LOCATED BETWEEN SAID END WALL AND ONE END OF SAID ACTUATOR FOR URGING SAID ACTUATOR IN ONE DIRECTION, SAID HOUSING HAVING AN OPEN END OPPOSITE SAID END WALL, SAID ACTUATOR HAVING AN ACTUATING PORTION NORMALLY EXTENDING OUTWARDLY OF SAID HOUSING THROUGH SAID OPEN END IN RESPONSE TO THE ACTION OF SAID BIASING MEANS, PROJECTING MEANS FORMED IN SAID ACTUATOR AND RECESS MEANS FORMED IN AT LEAST ONE OF THE SIDE LEGS OF SAID U, SAID PROJECTING MEANS BEING ADAPTED TO ENGAGE SAID RECESS MEANS WHEREBY THE WALL OF SAID RECESS MEANS ACTS AS A STOP FOR SAID ACTUATOR WHEN MOVED IN SAID ONE DIRECTION BY SAID BIASING MEANS, AN INSULATING MEMBER POSITIONED ADJACENT ONE WALL OF SAID ACTUATOR, MEANS FOR HOLDING SAID INSULATING MEMBER IN POSITION, A PLURALITY OF TERMINALS EXTENDING THROUGH SAID INSULATING MEMBER, A RECESS DEFINED BY SAID ACTUATOR, SAID ACTUATOR RECESS BEING DIMENSIONED SO THAT TWO OF SAID TERMINALS ARE ENCOMPASSED BY THE RECESS, A PAIR OF SPHERES IN SAID ACTUATOR RECESS BIASED TO ENGAGE A RESPECTIVE ONE OF SAID TWO TERMINALS AND ADAPTED TO BE ROLLED FROM THE RESPECTIVE TERMINALS UPON MOVEMENT OF SAID ACTUATOR IN OPPOSITION TO SAID SPRING TOWARD SAID END WALL WHEREBY ONE OF SAID SPHERES ENGAGES ANOTHER OF THE TWO TEMINALS WHILE THE OTHER OF SAID SPHERES ENGAGES A THIRD TERMINAL. 